Various types of record media supply and control devices have been designed in the prior art for the purpose of feeding printers, for accounting machines, billing machines, and other graphic-type devices.
Usually such printers are provided with a means for transporting a printing mechanism, usually an impact type printer, across the face of a platen (roller) where the printing takes place, and a means for feeding, or transporting, the train of paper (record media) to and around the platen where printing, typing or other activities may take place on the paper train. In such prior art devices, a separate servo motor was utilized to transport the printing mechanism across the platen for line printing and a separate servo motor was utilized to drive the transport mechanism for supplying the record media to the platen, with suitable timing controls provided so that the feeding of the record media did not interfere with the printing mechanism during the printing mode and proper columns and lines were thus formed.
The problem with such prior art devices is that the dual servo motor system, as separate drives of the printing mechanism transport and the media feed, significantly increased the cost and size and space requirements of such devices. As to single drive systems, while not practical in the past, the high speeds achievable with servo motor drives allow mechanical motions to be overlapped without significant impact on the thru-put of the device.